My first project Variac

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Cliff JonesSite Administrator

Join date : 2010-11-22

Subject: My first project Variac 2011-04-13, 12:23 am

I now have two meters to monitor my variac. One is a Simpson 3-1/2" Iron vane 5 amps AC, model 1357.The other meter is A Jewell 150 VAC 5" rectified.I will now have to design a wood box to include the variac, meters, AC plug, AC socket, in-line fuse, Power Light, power switch, and maybe include an isolation transformer in-line. I was also thinking of a light-bulb socket to do dim bulb-testing. I've got the basic wiring figured after following this layout, minus the meter designed in the circuit. Here a graphic of the one I plan to use:

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ve1arnModerator

Join date : 2010-11-23

Subject: Re: My first project Variac 2011-04-13, 9:54 am

Sorry Cliff, but I do not see any graphic. Maybe it's just me though.

Cliff JonesSite Administrator

Join date : 2010-11-22

Subject: Re: My first project Variac 2011-04-13, 11:07 am

OK thanks I'll tryand see whut hoppund again [You must be registered and logged in to see this image.]

I also found a simple program to make meter faces for free called meterbasic, it can be found at:[You must be registered and logged in to see this link.]

_________________I'm a Science Thinker, Radio Tinkerer, and all around good guy. Just ask Me!

Last edited by Cliff Jones on 2011-04-21, 6:11 pm; edited 1 time in total

ve1arnModerator

Join date : 2010-11-23

Subject: Re: My first project Variac 2011-04-14, 4:15 am

Hi Cliff,

Graphic worked that time.

I'm no expert here, but I tend to like the idea of the variac before the isolation transformer. I can't even say I have any real technical reason for that opinion either.

I like the circuit though. I have a used case with a 12 volt power supply and cooling fan in it that would make a great case for a unit like this. Once I take out the power supply that is.

Cheers for now, Bob

Cliff JonesSite Administrator

Join date : 2010-11-22

Subject: Re: My first project Variac 2011-04-21, 5:28 pm

I'm not a woodworker per-say but I guess I have to cobble a box together, getting some wood from ACE Hardware Or a Metal box. I do Have a small bench top Drill press and a Radial arm saw in the garage, so one way or the tuther, I'll get something going. Ive tried to make a diagram now I'll have to figure out the parts layout next.

_________________I'm a Science Thinker, Radio Tinkerer, and all around good guy. Just ask Me!

Cliff JonesSite Administrator

Join date : 2010-11-22

Subject: Just picked up 500 coin envelopes 2011-04-21, 5:36 pm

Decided to store my caps and resistors that way, went to Office Depot to get my computer memory, and off handedly asked if they carried coin envelopes, $ 19 for 500 count, guess another project now.

_________________I'm a Science Thinker, Radio Tinkerer, and all around good guy. Just ask Me!

Cliff JonesSite Administrator

Join date : 2010-11-22

Subject: Sad News 2012-06-05, 5:40 pm

I did get a General radio Variac with two meters, one is voltage and the second has two ranges in watts, with the maximum being 1400W. So my project will be put on hold for now. (I May have mentioned this in another post, but I fergit

_________________I'm a Science Thinker, Radio Tinkerer, and all around good guy. Just ask Me!

FrankBModerator

Join date : 2010-11-22

Subject: Re: My first project Variac 2012-11-25, 11:48 pm

Cliff-Do NOT ground the variac to the isolation tx output socket as shown in the schematic. That totally defeats the purpose of the isolation transformer. You might as well use the variac without the transformer. Key word here is "isolation". NOTE: THis pertains if you use anything with a 3 wire cord or has the neutral grounded to the power cord ground.

I found this out the hard way in tech school many decades ago. If you try to scope a piece of equipment plugged in with the ground hooked up you will either blow up the equipment, blow up the scope or other test equipment you are using, or blow the circuit breakers in the building.

The teacher knew nothing about "hot chassis" setups and after plunging the entire building & several classrooms into darkness 3 X in a row, I finally figured out what was going on.Not to mention you can fry your self easier also.

I typically use a Weller grounded tip soldering iron for repairs and with the 3 wire cord and the ground in place, I have made some mighty fine arcs with the soldering iron to a hot chassis even with the power switch "off", when the hot chassis is plugged in wrong, or if there is leakage thru the isolation line bypass caps inthe item under repair.